Randomized, placebo-controlled study on efficacy, safety and tolerability of drug-induced defibrinogenation for sudden sensorineural hearing loss: the lessons learned.

PURPOSE: Disturbance of cochlear microcirculation is discussed as final common pathway of various inner ear diseases. Hyperfibrinogenemia causing increased plasma viscosity is a possible factor for a critical reduction of cochlear blood flow that might lead to sudden sensorineural hearing loss (SSHL). The aim was to determine the efficacy and safety of drug-induced defibrinogenation by ancrod for SSHL. METHODS: Double-blind, randomized, placebo-controlled, multicenter, parallel group, phase II (proof-of-concept) study (planned enrollment: 99 patients). Patients received an infusion of ancrod or placebo (day 1) followed by subcutaneous administrations (day 2, 4, 6). Primary outcome was the change in pure tone audiogram air conduction average until day 8. RESULTS: The study was terminated early due to slow recruiting (31 enrolled patients: 22 ancrod, 9 placebo). A significant improvement of hearing loss was registered in both groups (ancrod: - 14.3 dB ± 20.4 dB, - 39.9% ± 50.4%; placebo: - 22.3 dB ± 13.7 dB, - 59.1% ± 38.0%). A statistically significant group-difference was not detected (p = 0.374). Placebo response of 33.3% complete and 85.7% at least partial recovery was observed. Plasma fibrinogen levels were reduced significantly by ancrod (baseline: 325.2 mg/dL, day 2: 107.2 mg/dL). Ancrod was tolerated well, no adverse drug reaction was of severe intensity, no serious adverse events occurred. CONCLUSION: Ancrod reduced fibrinogen levels that support its mechanism of action. The safety profile can be rated positively. Since the planned number of patients could not be enrolled, no efficacy conclusion can be drawn. The high rate of placebo response challenges clinical trials for SSHL and needs to be considered in future investigations. Trial registrations This study was registered in the EU Clinical Trials Register, EudraCT-No. 2012-000066-37 at 2012-07-02.

Pharmacological and genetic depletion of fibrinogen protects from kidney fibrosis.

Fibrinogen (Fg) has been implicated in the pathogenesis of several fibrotic disorders by acting as a profibrotic ligand for a variety of cellular surface receptors and by modulating the provisional fibrin matrix formed after injury. We demonstrated increased renal Fg expression after unilateral ureteral obstruction and folic acid (FA) nephropathy in mice, respectively. Urinary Fg excretion was also increased in FA nephropathy. Using in vitro and in vivo approaches, our results suggested that IL-6 mediates STAT3 activation in kidney fibrosis and that phosphorylated (p)STAT3 binds to Fgα, Fgß, and Fgγ promoters in the kidney to regulate their transcription. Genetically modified Fg heterozygous mice (∼75% of normal plasma Fg levels) exhibited only 3% kidney interstitial fibrosis and tubular atrophy after FA nephropathy compared with 24% for wild-type mice. Fibrinogenolysis through Ancrod administration after FA reduced interstitial fibrosis more than threefold compared with vehicle-treated control mice. Mechanistically, we show that Fg acts synergistically with transforming growth factor (TGF)-ß1 to induce fibroblast proliferation and activates TGF-ß1/pSMAD2 signaling. This study offers increased understanding of Fg expression and molecular interactions with TGF-ß1 in the progression to kidney fibrosis and, importantly, indicates that fibrinogenolytics like Ancrod present a treatment opportunity for a yet intractable disease.

Fibrinogen depleting agents for acute ischaemic stroke.

BACKGROUND: Fibrinogen depleting agents reduce fibrinogen in blood plasma, reduce blood viscosity and hence increase blood flow. This may help remove the blood clot blocking the artery and re-establish blood flow to the affected area of the brain after an ischaemic stroke. The risk of haemorrhage may be less than with thrombolytic agents. This is an update of a Cochrane review first published in 1997 and last updated in 2003. OBJECTIVES: To assess the effect of fibrinogen depleting agents in patients with acute ischaemic stroke. SEARCH METHODS: We searched the Cochrane Stroke Group Trials Register (July 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 7), the Chinese Stroke Trials Register (September 2011), MEDLINE (1950 to July 2011), EMBASE (1980 to July 2011) and Web of Science Conference Proceedings (1990 to July 2011). In addition, we searched six Chinese databases, four ongoing trials registers (July 2011) and relevant reference lists. For previous versions of the review, we handsearched journals and contacted researchers in China and Japan and relevant drug companies. SELECTION CRITERIA: Randomised trials of fibrinogen depleting agents started within 14 days of stroke onset, compared with control in patients with definite or possible ischaemic stroke. DATA COLLECTION AND ANALYSIS: Two review authors independently selected trials, assessed trial quality and extracted the data. We resolved disagreement by discussion. MAIN RESULTS: We included eight trials involving 5701 patients. Six trials tested ancrod and two trials tested defibrase (patients were treated for less than three hours to less than 48 hours). Allocation concealment was adequate in seven trials. Fibrinogen depleting agents marginally reduced the proportion of patients who were dead or disabled at the end of follow-up (risk ratio (RR) 0.95, 95% confidence Interval (CI) 0.90 to 0.99, 2P = 0.02). There was no statistically significant difference in death from all causes during the scheduled treatment or follow-up period. There were fewer stroke recurrences in the treatment group than in the control group (RR 0.67, 95% CI 0.49 to 0.92, 2P = 0.01). However, symptomatic intracranial haemorrhage was about twice as common in the treatment group compared with the control group (RR 2.42, 95% CI 1.65 to 3.56, 2P < 0.00001). AUTHORS' CONCLUSIONS: The current evidence is promising but not yet sufficiently robust to support the routine use of fibrinogen depleting agents for the treatment of acute ischaemic stroke. Further trials are needed to determine whether there is worthwhile benefit, and if so, which categories of patients are most likely to benefit.

Ancrod and fibrin formation: perspectives on mechanisms of action.

BACKGROUND AND PURPOSE: Ancrod, derived from Malayan pit viper venom, has been tested as ischemic stroke treatment in clinical trials with inconsistent results. We studied the actions of ancrod on fibrinolysis pathways in patient plasma samples and endothelial cell culture systems. METHODS: We analyzed fibrinogen levels during the first 6 hours of ancrod infusion in patients entered in the Stroke Treatment with Ancrod Trial. For the in vitro study, human brain microvascular endothelial cells incubated with plasminogen or with human brain microvascular endothelial cell-conditioned medium were co-incubated with ancrod and fibrinogen under normal or oxygen-glucose deprivation conditions over 6 hours. RESULTS: Fibrinogen levels decreased both in vivo and in vitro. Ancrod generated fibrinopeptide A, caused visible clot formation, and reduced levels of tissue-type plasminogen activator antigen in the human brain microvascular endothelial cell system and in a cell-free system with conditioned media. CONCLUSIONS: The in vitro results indicate that ancrod causes local fibrin formation and secondary depletion of tissue-type plasminogen activator by binding to fibrin clot. Ancrod-induced fibrin formation could result in cerebral microvascular occlusion and may explain the suboptimal clinical effects of ancrod in human stroke trials.

Intravenous ancrod for acute ischaemic stroke in the European Stroke Treatment with Ancrod Trial: a randomised controlled trial.

BACKGROUND: Intravenous tissue plasminogen activator is the only approved specific treatment for acute ischaemic stroke. Ancrod, a natural defibrinogenating agent from snake venom, has proved to have a favourable effect when given within 3 h after an acute ischaemic stroke. The European Stroke Treatment with Ancrod Trial was undertaken to assess the effects of ancrod when given within 6 h. METHODS: 1222 patients with an acute ischaemic stroke were included in this randomised double-blind placebo-controlled trial. Brain CT scans were done to exclude intracranial haemorrhages and large evolving ischaemic infarctions. Patients were randomly assigned ancrod (n=604) or placebo (n=618). The primary outcome was functional success at 3 months (survival, Barthel Index of 95 or 100, or return to prestroke level). The analysis was by intention-to-treat. This trial is registered with ClinicalTrials.gov, trial number NCT00343174. FINDINGS: Functional success at 3 months did not differ between patients given ancrod (42%) and those given placebo (42%) (p=0.94, OR=0.99, 95% CI, 0.76-1.29). INTERPRETATION: On the basis of our findings, ancrod should not be recommended for use in acute ischaemic stroke beyond 3 h.

Results of a systematic evaluation of treatment outcomes for heparin-induced thrombocytopenia in patients receiving danaparoid, ancrod, and/or coumarin explain the rapid shift in clinical practice during the 1990s.

INTRODUCTION: Randomized controlled trials evaluating treatment of acute, transient, but uncommon diseases are difficult to perform. The prothrombotic adverse drug reaction, heparin-induced thrombocytopenia (HIT), is such an example. During the mid-1980s, the defibrinogenating snake venom, ancrod (+/-warfarin, Canada), or coumarin (warfarin, Canada; phenprocoumon, Germany) alone, were often used to treat HIT. During the 1990s, danaparoid+/-coumarin began to replace ancrod (+/-coumarin), or coumarin alone, for treating HIT, despite danaparoid not being approved for treatment of HIT. METHODS: We performed a retrospective evaluation of treatment outcomes from 1986 to 1999, comparing danaparoid+/-coumarin (n=62) versus ancrod+/-coumarin or coumarin alone (controls, n=56). RESULTS: The predefined composite endpoint of adjudicated new, progressive, or recurrent thrombosis (including thrombotic death), or limb amputation, at day 7 (maximum, one event per patient) was significantly lower in danaparoid-treated patients, compared with controls: 8/62=12.9% (95% CI, 4.3-21.5) vs. 22/56=39.3% (95% CI, 26.1-52.5); p=0.0014. We also found a lower frequency of the composite endpoint at end of study (day 35) in danaparoid-treated patients: 12/62=19.4% vs. 24/56=42.9% (p=0.0088). Major bleeding (by day 7) occurred in 7/62 (11.3%) and 16/56 (28.6%) of danaparoid-treated and control patients, respectively (p=0.0211). CONCLUSIONS: The replacement of ancrod+/-coumarin, or coumarin alone, by danaparoid (+/-coumarin) in the mid-1990s for the treatment of HIT was justified by improved efficacy and safety.

Heparin-induced thrombocytopenia in the cardiovascular patient: diagnostic and treatment guidelines.

Heparin-induced thrombocytopenia/thrombosis is an immunologic reaction to unfractionated heparin characterized by thrombocytopenia, platelet activation and thrombosis. A high index of suspicion is required for timely diagnosis and treatment. Treatment is complex and outcome maybe less then satisfactory.

Antithrombotic trials in acute ischaemic stroke: a selective review.

Stroke is a common cause of morbidity and mortality throughout the US and the world. Given the highly disabling nature of this disease, it is important to provide acute therapy when indicated to improve individual outcomes. Recombinant tissue plasminogen activator (rt-PA) is, at present, the only approved drug for the treatment of acute strokes due to cerebral ischaemia. It can be given intravenously within a 3-h window of the onset of neurological deficits. Intra-arterial administration of rt-PA within a 6-h window is performed at several academic centres in patients with middle cerebral and other intracranial artery occlusions based on results of a randomised clinical trial. Other thrombolytic agents are being studied in randomised trials. Although acute therapy of ischaemic stroke has received much attention since the approval of rt-PA, only a small percentage of individuals actually receive rt-PA. This article will review the main thrombolytic agents and the trials performed thus far, as well as examine some important ongoing trials. How administration of acute thrombolytic therapy may evolve in the future will also be addressed.

Bivalirudin, blood loss, and graft patency in coronary artery bypass surgery.

A safe and effective alternative is needed for patients in whom unfractionated heparin (UFH) or protamine is contraindicated (e.g., those with heparin-induced thrombocytopenia or allergy to protamine). Furthermore, choice of anticoagulant may influence graft patency in coronary surgery and may therefore be important even when there is no contraindication to UFH. Direct thrombin inhibitors have several potential advantages over UFH, demonstrated in acute coronary syndromes. However, there are also potential difficulties with their use related to lack of reversal agents and paucity of clinical experience in monitoring their anticoagulant activity at the levels required for cardiac surgery with cardiopulmonary bypass (CPB). In the first prospective randomized trial of an alternative to heparin in cardiac surgery, we compared bivalirudin (a short-acting direct thrombin inhibitor) with UFH in 100 patients undergoing off-pump coronary artery bypass (OPCAB) surgery. Blood loss for the 12 hours following study drug initiation in the bivalirudin group was not significantly greater than in the heparin group. Median graft flow was significantly higher in the bivalirudin group. We concluded that anticoagulation for OPCAB surgery with bivalirudin was feasible without a clinically important increase in perioperative blood loss. A larger study is needed to investigate the impact of improved graft patency on other clinical outcomes after cardiac surgery.

Fibrinogen depleting agents for acute ischaemic stroke.

BACKGROUND: Fibrinogen depleting agents reduce fibrinogen in blood plasma, reduce blood viscosity and hence increase blood flow. This may help remove the blood clot blocking the artery and re-establish blood flow to the affected area of the brain after an ischaemic stroke. The risk of haemorrhage may be less than with thrombolytic agents. OBJECTIVES: The objective of this review was to assess the effect of fibrinogen depleting agents in patients with acute ischaemic stroke. SEARCH STRATEGY: We searched the Cochrane Stroke Group Trials Register (last searched May 2003). In addition we searched the following electronic databases: EMBASE (1980-October 2001), China Biological Medicine Database (CBM-disc 1981- December 2002), Chinese Stroke Trials Register (1996 - December 2002) and Index of Scientific and Technical Proceedings (Web of Science Proceedings [1990-October 2001]). We handsearched relevant journals and contacted Chinese and Japanese researchers and drug companies. SELECTION CRITERIA: Randomised and quasi-randomised trials of fibrinogen depleting agents started within 14 days of stroke onset, compared with control in patients with definite or possible ischaemic stroke. DATA COLLECTION AND ANALYSIS: Two reviewers independently applied the inclusion criteria, assessed trial quality and extracted the data. MAIN RESULTS: Five trials involving 2926 patients were included. A further trial (ESTAT) has not yet been published in full. Four trials tested ancrod and one trial tested defibrase. Allocation concealment was adequate in four trials. Fibrinogen depleting agents moderately reduced the proportion of patients who were dead or disabled at the end of follow up (Relative risk [RR] 0.90, 95% Confidence Interval [CI] 0.82 to 0.98, 2P=0.02). There was no statistically significant difference in death from all causes during the scheduled treatment period (RR 0.71, 95% CI 0.44 to 1.13) and at the end of follow-up (RR 0.98, 95% CI 0.78 to 1.24). There was a non-significant excess of symptomatic intracranial haemorrhages with treatment (RR 2.64, 95%CI 0.96 to 7.30, 2P=0.06). REVIEWER'S CONCLUSIONS: Fibrinogen depleting agents are promising. However more data, particularly ESTAT data, are needed before more reliable conclusions can be drawn.

Ancrod.

Ischaemic stroke occurs in over 500,000 US residents each year. Most strokes are due to embolic or thrombotic occlusion of an artery to the brain. Strategies to reduce thrombus formation and to improve blood flow in the compromised arterial bed have been have been a major focus of management with the goal of improving the outcome of ischaemic stroke. Ancrod is a biological agent extracted from the venom of the Malayan pit viper that reduces blood fibrinogen levels. This action prolongs blood clot formation and lowers blood viscosity. Ancrod has been studied in a variety of ischaemic conditions including stroke. The clinical studies of ancrod in patients with stroke have shown a benefit with ancrod treatment in neurological outcome with only a modest increase in bleeding risk.

Stroke trials: what have we learned?

We reviewed the recent, major, therapeutic trials of intravenous thrombolytic therapy and ancrod for ischemic stroke. Randomized, controlled studies of acute ischemic stroke treatment were reviewed. Several post-FDA approval intravenous tPA studies were reviewed to understand the experience of this medication in practice. STAT trial was the major study using ancrod. Of multiple intravenous thrombolytic studies, the NINDS study of intravenous tPA was the only study to demonstrate a significantly higher percentage of patients with complete recovery or minimal deficit at three months. Studies in communities utilizing intravenous tPA for stroke illustrate the need for close adherence to the NINDS study protocol or else the risk of tPA use may exceed the benefits.

Current concepts in the management of acute ischemic stroke.

The treatment of stroke is multifaceted, and is governed by three, well established goals: 1) To minimize the extent of brain; 2) To medically support the stroke patient; and 3) To prevent further brain injury secondary to initial event or repeated vascular insults. Certain guidelines for emergency care, based on clinical experience and knowledge of pathophysiology, have been accepted in many institutions as the standard. This article provides guidelines about the current management of acute ischemic stroke based on currently available data from clinical trials. The target audiences for this article are emergency room physicians and neurologists, who manage the patients during the first few hours after stroke.

Optimal timing of thrombolytic therapy in acute ischaemic stroke.

The clinical benefit of thrombolytic therapy for patients experiencing acute cerebral ischaemia has been demonstrated by both clinical trials and phase IV studies. However, such treatments must be initiated in a rapid manner, with treating physicians adhering to strict protocols designed to minimise delays and maximise safety. The efficacy of intravenous drug administration has been established with alteplase (recombinant tissue plasminogen activator; tPA) and ancrod, but only if these drugs can be administered within 3 hours of symptom onset. The use of alteplase beyond this timeframe, or outside of established protocols, may be hazardous. The use of alternative intravenous thrombolytic agents, such as streptokinase, also appears hazardous. Intra-arterial delivery of thrombolytic drugs such as pro-urokinase may extend clinical benefit to the 6-hour time frame.

Cost-effectiveness of ancrod treatment of acute ischaemic stroke: results from the Stroke Treatment with Ancrod Trial (STAT).

RATIONALE, AIMS AND OBJECTIVES: This paper describes a recent randomized controlled trial in which 42% of patients receiving ancrod attained a favourable outcome in comparison with 34% of controls. Although the above effect size corresponds to a number needed to treat (to achieve a favourable outcome) of approximately 13, intuition does not necessarily suggest what would be the overall impact of a treatment with this level of efficacy. METHODS: The objective was to evaluate the cost-effectiveness of ancrod. Cost-effectiveness analysis of data from the Stroke Treatment with Ancrod Trial (STAT) trial was carried out. The participants were 495 patients with data on functional status at the conclusion of follow-up. Short-term results were based upon utilization and quality of life observed during the trial; these were merged with expected long-term results obtained through simulation using the Stroke Policy Model. The main outcome measure was incremental cost-effectiveness ratio. RESULTS: Ancrod treatment resulted in both better quality-adjusted life expectancy and lower medical costs than placebo as supported by sensitivity analysis. The cost differential was primarily attributable to the long-term implications of ancrod's role in reducing disability. CONCLUSIONS: If ancrod is even modestly effective, it will probably be cost-effective (and, indeed, cost-saving) as well. The net population-level impact of even modestly effective stroke treatments can be substantial.

Stroke--acute interventions.

The reduction of blood flow to parts of the brain is the cause of ischemic stroke leading to functional deficits and, if prolonged, to irreversible neurological and morphological defects. The fast reperfusion, therefore is the most important therapeutic strategy and was proven to be effective in clinical trials. Steps to intervene with secondary biochemical, molecular, or inflammatory disturbances were not successful so far. Since direct therapeutic interventions are limited, the general management of the stroke victim is of utmost importance--and was shown to be most successful in dedicated stroke units. Acute therapeutic interventions in ischemic stroke can only be successful as long as tissue in the area of the ischemic compromise is still viable. The area of irreversible damage can be identified and distinguished from the penumbral zone, i.e., tissue with impaired function but preserved morphology by functional imaging modalities, like positron emission tomography (PET) or perfusion-(PW) and diffusion-weighted (DW) magnetic resonance imaging (MRI). In such studies it was demonstrated that a large portion of the final infarct is irreversibly affected in the first few hours in many patients. A considerable tissue volume is viable but critically hypoperfused; a smaller portion of the final infarct is sufficiently perfused and in this area secondary and delayed biochemical and molecular mechanisms contribute to the damage. Based on this concept the improvement of perfusion within the time window of opportunity must be the primary goal in treatment of ischemic stroke, and neuroprotective and other strategies can only play a supportive and additive role. That this is the case can be seen from the results of many controlled therapeutic trials, in which up to now only thrombolytic therapy with a 3 h time window for systemic and a 6 h time window for intraarterial application proved its efficacy, whereas all trials with neuroprotective, anti-inflammatory or anti-apoptotic strategies failed. Since the direct treatment strategies are limited the acute management of stroke victims is of utmost importance: This can be achieved optimally in dedicated stroke units in which the outcome was significantly improved over the regular care. It is still to be investigated if invasive strategies--e.g., craniectomy and hypothermia--or the combination of reperfusion and neuroprotective therapy can improve the outcome after ischemic stroke.

[Clinical study on effect of Agkistrodon antithrombogenase in auxiliary treatment of rheumatoid arthritis].

OBJECTIVE: To explore the clinical effect of Agkistrodon antithrombogenase (AAT) in the treatment of rheumatoid arthritis (RA) and its possible mechanism. METHODS: Besides the conventional non-steroid anti-inflammatory agents and disease-modifying anti-rheumatic drug, patients were treated supplementally with intravenous injection of AAT. The intracutaneous test showed allergic to AAT patients were treated with Salvia injection and taken as control group. Changes of related clinical indexes in the two groups were observed. RESULTS: After 3 weeks treatment, condition of patients in both groups were improved clinically in joint swollen index, joint tenderness index, morning stiffness time, pain assessment (VAS) and health assessment questionnaire (HAQ) on daily life activity as well as ESR level (P < 0.05 or P < 0.01), with the VAS, HAQ and fibrinogen levels more significantly improved than those of control (P < 0.05 or P < 0.01), and the total effective rate higher in the AAT treated group than those in the control group (P < 0.05). CONCLUSION: AAT has good effect on easing clinical symptoms of RA possibly through anti-inflammation and improving the microcirculation with less toxic and adverse reaction, so is worthy of recommendation.

Alternatives to unfractionated heparin for anticoagulation in cardiopulmonary bypass.

Despite the progress made in the development of cardiopulmonary bypass (CPB) equipment, systemic anticoagulation with unfractionated heparin and post-bypass neutralization with protamine are still used in most perfusion procedures. However, there are a number of situations where unfractionated heparin, protamine or both cannot be used for various reasons. Intolerance of protamine can be addressed with extracorporeal heparin removal devices, perfusion with (no) low systemic heparinization and, to some degree, by perfusion with alternative anticoagulants. Various alternative anticoagulation regimens have been used in cases of intolerance to unfractionated heparin, including extreme hemodilution, low molecular weight heparins, danaparoid, ancrod, r-hirudin, abciximab, tirofiban, argatroban and others. In the presence of heparin-induced thrombocytopenia (HIT) and thrombosis, the use of r-hirudin appears to be an acceptable solution which has been well studied. The main issue with r-hirudin is the difficulty in monitoring its activity during CPB, despite the fact that ecarin coagulation time assessment is now available. A more recent approach is based on selective blockage of platelet aggregation by means of monoclonal antibodies directed to GPIIb/IIIa receptors (abciximab) or the use of a GPIIb/IIIa inhibitor (tirofiban). An 80% blockage of the GPIIb/IIIa receptors and suppression of platelet aggregation to less than 20% allows the giving of unfractionated heparin and running CPB in a standard fashion despite HIT and thrombosis. Likewise, at the end of the procedure, unfractionated heparin is neutralized with protamine as usual and donor platelets are transfused if necessary. GPIIb/IIIa inhibitors are frequently used in interventional cardiology and, therefore, are available in most hospitals.